Tables explaining the JMA Seismic Intensity Scale
Notes(1) As a rule, seismic intensities announced by JMA are values observed using seismic intensity
meters installed on the ground or on the first floor of low-rise buildings. This document
describes the phenomena and damage that may be observed for individual seismic intensity
levels. Seismic intensities are not determined from the observed phenomena described here.
(2) Seismic ground motion is significantly influenced by underground conditions and topography.
Seismic intensity is the value observed at a site where a seismic intensity meter is installed,
and may vary even within the same city. In addition, the amplitude of seismic motion generallydiffers by floor and location within the same building, as shaking on upper floors may beconsiderably amplified.
(3) Sites with the same level of seismic intensity will not necessarily suffer the same degree ofdamage, as the effect of tremors depends on the nature of the seismic motion (such as
amplitude, period and duration), the type of construction and underground conditions.
(4) This document describes typical phenomena that may be seen at individual levels of seismicintensity. In some cases, the level of damage may be greater or less than specified. Not allphenomena described for each intensity level may necessarily occur.
(5) The information outlined here is regularly checked at intervals of about five years, and isupdated in line with actual phenomena observed in new cases or improvements in theearthquake resistance of buildings and structures.

●Human perception and reaction, indoor situation, outdoor situation
Seismicintensity

Human perception andreaction

Indoor situation

Outdoor situation

0

Imperceptible to people, but recordedby seismometers.

－－

1

Felt slightly by some people keeping
quiet in buildings.

－－

2

Felt by many people keeping quiet inbuildings. Some people may beawoken.

Hanging objects such as lamps swing
slightly.

－3Felt by most people in buildings. Felt
by some people walking. Many people
are awoken.

Dishes in cupboards may rattle.

1

Electric wires swing slightly.

Seismicintensity

4

Human perception andreaction

Indoor situation

Most people are startled. Felt by most Hanging objects such as lamps swing
people walking. Most people aresignificantly, and dishes in cupboards
awoken.
rattle. Unstable ornaments may fall.

Outdoor situation

Electric wires swing significantly.
Those driving vehicles may notice thetremor.

Hanging objects such as lamps swing
violently. Dishes in cupboards and items
In some cases, windows may break andon bookshelves may fall. Many unstablefall. People notice electricity poles
ornaments fall. Unsecured furniture
moving. Roads may sustain damage.
may move, and unstable furniture may
topple over.

5 Lower

Many people are frightened and feelthe need to hold onto something
stable.

5 Upper

Windows may break and fall,
Dishes in cupboards and items on unreinforced concrete-block walls may
Many people find it hard to move;bookshelves are more likely to fall. TVs collapse, poorly installed vending
walking is difficult without holding
may fall from their stands, and machines may topple over, automobiles
onto something stable.
unsecured furniture may topple over.
may stop due to the difficulty ofcontinued movement.

6 Lower It is difficult to remain standing.

Many unsecured furniture moves andWall tiles and windows may sustain
may topple over. Doors may become
damage and fall.
wedged shut.

6 UpperWall tiles and windows are more likely
Most unsecured furniture moves, and is
to break and fall. Most unreinforced
more likely to topple over.
concrete-block walls collapse.

It is impossible to remain standing or
move without crawling. People may bethrown through the air.

7

Most unsecured furniture moves and Wall tiles and windows are even more
topples over, or may even be thrown likely to break and fall. Reinforced
through the air.
concrete-block walls may collapse.

2● Wooden houses
Seismic
intensity

Wooden houses
High earthquake resistance

Low earthquake resistance

5 Lower－Slight cracks may form in walls.

5 Upper－

Cracks may form in walls.

6 Lower

Slight cracks may form in walls.

Cracks are more likely to form in walls.
Large cracks may form in walls.
Tiles may fall, and buildings may lean or collapse.

6 Upper

Cracks may form in walls.

Large cracks are more likely to form in walls.
Buildings are more likely to lean or collapse.

Cracks are more likely to form in walls.
Buildings may lean in some cases.

Buildings are even more likely to lean or collapse.

7(Note 1) Wooden houses are classified into two categories according to their earthquake resistance, which tends to be higher for newerfoundations. Earthquake resistance tends to be low for structures built up to 1981, and high for those built since 1982. However, tomaintain a certain range of earthquake resistance according to differences in structure and wall arrangement, resistance is notnecessarily determined only by foundation age. The earthquake resistance of existing buildings can be ascertained throughquakeproofing diagnosis.
(Note 2) The walls in this table are assumed to be made of mud and/or mortar. Mortar in a wall with a weak base can easily break off
and fall, even under conditions of low deformation.
(Note 3) Damage to wooden houses depends on the period and duration of seismic waves. In some cases (such as the Iwate-Miyagi
Nairiku Earthquake of 2008), few buildings sustain damage in relation to the level of seismic intensity observed.

● Reinforced-concrete buildings
Seismicintensity

5 Upper
6 Lower

Reinforced-concrete buildings
High earthquake resistance

Low earthquake resistance－Cracks may form in walls, crossbeams and pillars.
Cracks are more likely to form in walls, crossbeams andpillars.

Cracks may form in walls, crossbeams and pillars.

6 Upper

Cracks are more likely to form in walls, crossbeams andpillars.

7

Cracks are even more likely to form in walls, crossbeams
and pillars.
Ground level or intermediate floors may sustain
significant damage. Buildings may lean in some cases.

Slippage and X-shaped cracks may be seen in walls,crossbeams and pillars.
Pillars at ground level or on intermediate floors may
disintegrate, and buildings may collapse.
Slippage and X-shaped cracks are more likely to be seen inwalls, crossbeams and pillars.
Pillars at ground level or on intermediate floors are more
likely to disintegrate, and buildings are more likely tocollapse.

(Note 1) Earthquake resistance tends to be higher for newer foundations. The value tends to be low for structures built up to 1981, andhigh for those built since 1982. However, to maintain a certain range of earthquake resistance according to differences in structureand 2D/3D arrangement of reinforced walls, resistance is not necessarily determined only by foundation age. The earthquake
resistance of existing buildings can be ascertained through quakeproofing diagnosis.
(Note 2) Slight cracks may form in reinforced-concrete buildings without their core structure being affected.

3

● Situation of ground and slopes, etc.
Seismic
intensitySituation of ground

Situation of slopes, etc.

5 Lower
Small cracks may form and liquefaction※1 may occur.

Rock falls and landslips may occur.

Cracks may form.

Landslips and landslides may occur.

5 Upper
6 Lower
6 Upper

Landslips are more likely to occur; large landslides andLarge cracks may form.

massif collapses may be seen※2.

7※1 Liquefaction may be seen in areas with a high groundwater level and loose sand deposits. Damage observed as a result ofliquefaction includes spouts of muddy water from the ground, outbreaks of subsidence in riverbanks and quays, elevation of sewage
pipes and manholes, and leaning or destruction of building foundations.
※2 When large landslides and massif collapses occur, dams may form depending on geographical features, and debris flow may occur
due to the large quantities of sediment produced.

● Influence on utilities and infrastructure, etc.
Suspension of gas supply
Suspension of water supply,
electrical blackouts
Suspension of railroad
services, regulation ofhighways, etc.
Disruption to lines ofcommunication such astelephones
Suspension of elevator
services

In the event of shaking with a seismic intensity of about 5 Lower or more, gas meter withsafety devices are tripped, stopping the supply of gas.
In the event of stronger shaking, the gas supply may stop for entire local blocks※.
Suspension of water supply and electrical blackouts may occur in regions experiencing shaking
with a seismic intensity of about 5 Lower or more※.
In the event of shaking with a seismic intensity of about 4 or more, services on railroads or
highways may be stopped for safety confirmation. Speed control and traffic regulations areperformed according the judgment of the relevant bodies. (Standards for safety confirmationdiffer by organization and area.)In the event of an earthquake, telephone line congestion may occur as a result of increased use
related to safety confirmation around regions of strong shaking.
To combat this, telecommunications providers offer message boards and message dial services
for use in disasters resulting from earthquakes with a seismic intensity of about 6 Lower ormore.
In the event of shaking with a seismic intensity of about 5 Lower or more, elevators withearthquake control devices will stop automatically for safety reasons. Resumption of service
may be delayed until safety is confirmed.

※ In the event of shaking with a seismic intensity of 6 Upper or more, gas, water and electric supplies may stop over wide areas.

● Effects on large-scale structures
Shaking of skyscrapers fromlong-period ground motion※

Sloshing of oil tanks

Due to their longer characteristic period, skyscrapers react less to earthquakes than generalreinforced-concrete buildings, which have a shorter characteristic period. However, theyexhibit slow shaking over a long time in response to long-period ground motion. If motion isstrong, poorly fixed office appliances may move significantly, and people may have to hold onto
stable objects to maintain their position.
Sloshing of oil tanks occurs in response to long-period ground motion. As a result, oil outflows
or fires may occur.

Damage or collapse of ceilings In institutions covering large spaces such as gymnasiums or indoor pools, ceilings may shakeetc. at institutions covering significantly and sustain damage or collapse, even in cases where ground motion is not severe
enough to cause other structural damage.
large spaces※ Occasionally, when a large earthquake occurs, long-period seismic waves reach locations far from the hypocenter; such waves may
be amplified over plains depending on the characteristic period of the ground, thus extending their duration.

4